CN113104153A

CN113104153A - Marine transfer trestle wave compensation control system and working method thereof

Info

Publication number: CN113104153A
Application number: CN202110450038.9A
Authority: CN
Inventors: 杜佳璐; 刘文吉; 孙明玮
Original assignee: Dalian Maritime University
Current assignee: Dalian Maritime University
Priority date: 2021-04-25
Filing date: 2021-04-25
Publication date: 2021-07-13
Anticipated expiration: 2041-04-25
Also published as: CN113104153B

Abstract

The invention discloses a wave compensation control system of an offshore transfer trestle and a working method thereof. According to the invention, the relative movement measuring unit comprising the 2D laser radar obtains the relative displacement between the front end of the transfer trestle bridge body after the leaning on and the transfer point on the target ship, so that the follow-up control of the front end of the transfer trestle bridge body and the transfer point on the target ship is conveniently realized. The invention adopts a time sequence method to forecast the movement of the transfer trestle base along with the ship and the relative displacement of the transfer trestle body front end and the transfer point on the target ship in an extremely short period, further adopts an active disturbance rejection control technology to realize the cooperative motion synchronous control of the hydraulic actuating mechanism of the transfer trestle, actively and synchronously compensates the disturbance of the ship swaying movement caused by waves to the transfer trestle, and can ensure that a control system obtains stronger anti-jamming capability and higher control precision.

Description

Marine transfer trestle wave compensation control system and working method thereof

Technical Field

The invention relates to equipment control technology in the field of ships and ocean engineering, in particular to a wave compensation control system for an offshore transfer trestle and a working method thereof, which can compensate the disturbance of the swaying motion of two side boats on the offshore transfer trestle in real time and ensure the safe transfer of personnel between the two side boats.

Background

The oil exploration ship is used for deepwater oil exploration operation, carries equipment for drilling and the like, and has a plurality of shipborne equipment and limited cabins, so that fewer crew members can be accommodated, and personnel transfer between ships is required to be carried out by carrying a shift-changing ship and the side of the oil exploration ship at intervals. The oil exploration ship is called a host ship, a dynamic positioning system is installed on the oil exploration ship, the shift ship is called a target ship, the target ship is connected with the host ship by a cable and a fender, the offshore transfer trestle is placed on the host ship, and an offshore personnel transfer passage can be established between the host ship and the target ship. In practice, due to the influence of ocean environments such as wind, waves and currents, the host ship and the target ship can generate motions with six degrees of freedom including rolling, pitching, yawing and heaving, and the swinging motions can generate disturbance on the transfer trestle and cause potential safety hazards for the transfer of offshore personnel.

Chinese patent CN108371766B discloses a position compensation retractable landing stage control system and its working method, including a position compensation control system and a position compensation hydraulic system, which actively controls the turning, retracting and pitching mechanisms of the landing stage to compensate the movement of the ship, so that the front end of the landing stage follows the lap joint point of the ship, to realize safe lap joint, and after the lap joint is completed, the turning, retracting and pitching mechanisms all enter a passive compensation mode, which can be used for personnel and material transfer between the ships at sea, but the landing stage requires that the ship at which the landing stage is located and the ship to be lapped are both installed with a dynamic positioning system, and requires that the front end of the landing stage and the ship to be lapped are both installed with a movement reference unit MRU, which is high in cost and has high requirements for the configuration of the ship to be lapped.

The invention Chinese patent CN107430010B discloses an electric sea wave active compensation boarding system and a control method thereof, the system comprises a roll compensation mechanism, a pitch compensation mechanism, a telescopic compensation mechanism, a pose detection system, a motion control system and an electric system, the active compensation of sea waves is realized by controlling a three-degree-of-freedom electric mechanism, and maintenance personnel can be ensured to safely and reliably walk on an offshore wind turbine platform from a ship, but the sea wave compensation control of the invention ensures that the boarding point position of the tail end of the boarding system in contact with the offshore wind turbine platform is relatively unchanged, namely the boarding point is fixed, and the invention is only suitable for transporting personnel and equipment from the ship to the offshore wind turbine platform and is not suitable for personnel transfer between two ships at sea.

The invention can not synchronously compensate the disturbance of the ship motion to the trestle, and can not ensure that the trestle body always keeps a fixed angle with the horizontal plane, thereby influencing the comfort of personnel transfer and the safety of cargo transfer.

Disclosure of Invention

The invention provides a wave compensation control system of an offshore transfer trestle and a working method thereof, which can actively and synchronously compensate the disturbance of the shaking motion of two close ships to the transfer trestle according to the real-time detected shaking motion of a host ship and the relative displacement of the front end of the bridge body of the transfer trestle and a transfer point on a target ship by controlling the cooperative motion of a hydraulic actuating mechanism of the transfer trestle, can control the front end of the bridge body of the transfer trestle to follow the transfer point on the target ship before the trestle is lapped, ensure safe lapping, ensure that the bridge body of the transfer trestle keeps an expected safe angle with the horizontal plane after lapping, and provide guarantee for the safe transfer of a shift worker among offshore ships through the transfer trestle.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the utility model provides a marine landing stage wave compensation control system that transfers, marine landing stage that transfers includes heave mechanism, rotation mechanism, every single move mechanism and bridge body telescopic machanism, wave compensation control system include hydraulic actuator, measurement system, electro-hydraulic servo valve, wave compensation control unit, control box, PLC and main control computer.

The hydraulic actuating mechanism comprises a hydraulic cylinder, a first hydraulic motor, a second hydraulic motor and a third hydraulic motor, wherein the hydraulic cylinder is used for driving a heave mechanism of the transfer trestle to stretch out and draw back, the first hydraulic motor is used for driving a swing mechanism of the transfer trestle to rotate, the second hydraulic motor is used for driving a pitching mechanism of the transfer trestle to pitch, and the third hydraulic motor is used for driving a bridge body stretching mechanism of the transfer trestle to stretch out and draw back;

the measuring system comprises a first encoder, a second encoder, a third encoder, a stay wire displacement sensor, a fourth encoder, an inclination angle sensor, an attitude sensor, a 2D laser radar, a transfer point monitoring device and a relative movement measuring unit, wherein the first encoder is arranged on a first hydraulic motor and used for measuring the rotation quantity of the first hydraulic motor and obtaining the rotation angle of the slewing mechanism; the second encoder is arranged on the second hydraulic motor and used for measuring the rotation quantity of the second hydraulic motor; the third encoder is arranged on the third hydraulic motor and used for measuring the rotation quantity of the third hydraulic motor and obtaining the stretching quantity of the bridge body stretching mechanism; the stay wire displacement sensor is arranged on the hydraulic cylinder and used for measuring the displacement of the heave mechanism; the fourth encoder is used for measuring the pitch angle of the pitch mechanism; the inclination angle sensor is arranged on the transfer trestle bridge body and is used for measuring an included angle formed by the transfer trestle bridge body and a horizontal plane; the attitude sensor is arranged at the geometric center of the transfer trestle base on the host ship and is used for measuring the heave displacement, the sway displacement and the roll angle of the transfer trestle base along with the ship; the 2D laser radar is arranged on a deck near a side board of the host ship close to one side of the target ship and used for scanning a topside strake and a deck area of the target ship to obtain a point cloud data frame containing geometric shape information of a scanned area; the transfer point monitoring device is arranged at the front end of the bridge body of the transfer trestle and comprises a camera and a laser sensor; the camera shoots the area where the transfer point on the target ship is located and is used for monitoring the transfer point on the target ship; the laser sensors comprise a first laser sensor and a second laser sensor which are respectively arranged on two sides of the front end of the transfer trestle bridge body and are used for measuring the distance between the two sides of the front end of the transfer trestle bridge body and a target ship deck; the relative motion measuring unit is used for obtaining the relative displacement between the front end of the transfer trestle bridge body and a transfer point on the target ship;

the electro-hydraulic servo valves are respectively a first electro-hydraulic servo valve, a second electro-hydraulic servo valve, a third electro-hydraulic servo valve and a fourth electro-hydraulic servo valve, and the first electro-hydraulic servo valve, the second electro-hydraulic servo valve, the third electro-hydraulic servo valve and the fourth electro-hydraulic servo valve are respectively used for controlling the hydraulic oil flow of the first hydraulic motor, the second hydraulic motor, the third hydraulic motor and the hydraulic cylinder;

the wave compensation control unit comprises a filter, a host ship motion forecasting module, a relative motion forecasting module, a first motion amplitude limiting module, a first kinematic inverse solution module, a three-degree-of-freedom compensation controller, a second motion amplitude limiting module, a second kinematic inverse solution module and a heave compensation controller;

the filter receives the expansion amount of the bridge expansion mechanism measured by the third encoder, the included angle between the transfer trestle bridge and the horizontal plane measured by the tilt angle sensor, the pitch angle of the pitch mechanism measured by the fourth encoder, and the heave displacement, the roll displacement and the roll angle of the transfer trestle base along with the ship measured by the attitude sensor, and outputs the filter value of the received information;

the host ship motion forecasting module receives the filter value from the filter, applies a time series method to carry out extremely short-term forecasting on the heave displacement, the sway displacement and the roll angle of the transfer trestle base along with the ship, and outputs forecast values of the heave displacement, the sway displacement and the roll angle of the transfer trestle base along with the ship at the next control moment;

the relative motion prediction module receives the relative displacement of the front end of the transfer trestle bridge body from the relative motion measurement unit and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction, carries out extreme short-term prediction on the relative displacement of the front end of the transfer trestle bridge body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction by applying a time sequence method, and outputs the prediction values of the relative displacement of the front end of the transfer trestle bridge body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction at the next control moment;

the first motion amplitude limiting module receives forecast values from a host ship motion forecasting module and a relative motion forecasting module, plans motion tracks of the slewing mechanism, the pitching mechanism and the bridge body stretching mechanism according to displacement, speed and acceleration constraint conditions caused by physical limitations of the slewing mechanism, the pitching mechanism and the bridge body stretching mechanism, and generates three hydraulic motor control instruction signals meeting the motion constraint conditions of the slewing mechanism, the pitching mechanism and the bridge body stretching mechanism;

the first kinematic inverse solution module receives three hydraulic motor control command signals generated by the first kinematic amplitude limiting module and calculates the respective expected rotation quantity of the three hydraulic motors;

the three-degree-of-freedom compensation controller receives the expected rotation quantity of each of the three hydraulic motors from the first kinematic inverse solution module, and obtains control voltages of the corresponding first electro-hydraulic servo valve, the second electro-hydraulic servo valve and the third electro-hydraulic servo valve, which are required by the expected rotation quantity of each hydraulic motor, through a three-degree-of-freedom active disturbance rejection compensation control law; the working mode of the three-degree-of-freedom compensation controller is called as an active compensation mode;

the second motion amplitude limiting module receives the expansion amount of the bridge body expansion mechanism from the filter, an included angle formed by a bridge body and a horizontal plane and a filtering value of a pitch angle of the pitching mechanism, plans the motion trail of the heave mechanism according to the constraint conditions of displacement, speed and acceleration caused by the physical limitation of the heave mechanism, and generates a hydraulic cylinder control instruction signal meeting the motion constraint conditions of the heave mechanism;

the second kinematic inverse solution module receives a hydraulic cylinder control instruction signal from the second kinematic amplitude limiting module, and calculates the expected expansion amount of the hydraulic cylinder according to a control target of the transfer trestle, namely, the transfer trestle body and the horizontal plane always keep a certain safe angle unchanged;

the heave compensation controller receives the expected telescopic quantity of the hydraulic cylinder from the second kinematic inverse solution module, and the control voltage of a fourth electro-hydraulic servo valve required by the expected telescopic quantity of the hydraulic cylinder is obtained through an auto-disturbance rejection heave compensation control law; the working mode of the heave compensation controller is called a heave compensation mode;

the control box is arranged on the deck of the host ship; the PLC is arranged in the control box and is used for realizing the functions of the filter, the first motion amplitude limiting module, the three-degree-of-freedom compensation controller, the second motion amplitude limiting module and the heave compensation controller; the main control computer is arranged in the control box and is used for realizing the functions of the first kinematics inverse solution module, the second kinematics inverse solution module, the relative motion measurement unit, the host ship motion forecast module and the relative motion forecast module.

Further, the area scanned by the 2D laser radar always includes the feature point M on the target ship, and the point cloud data frame obtained by the 2D laser radar is composed of N distance data, and the obtained point cloud data frame is sent to the main control computer.

Further, the laser beam of the laser sensor always keeps vertical and horizontal surfaces and downwards emits to the deck of the target ship.

Furthermore, the filter is a low-pass filter for filtering high-frequency signals contained in the attitude sensor measurement signal and the tilt sensor measurement signal, which are caused by deck high-frequency vibration caused by operations of equipment such as a marine main engine.

Further, the very short term forecast is forecast of time within a control period.

Further, the working method of the relative movement measuring unit comprises the following steps:

s1, preprocessing the point cloud data frame obtained by the 2D laser radar

Firstly, intercepting each frame of point cloud data from within a 2D laser radar scanning angle psi to obtain a point cloud data frame consisting of N distance data, wherein N is less than N; then, calculating an absolute value | Data [ m ] -Data [ m-1] | of the difference between the mth distance Data and the mth-1 distance Data in each frame of point cloud Data, and calculating a change rate ξ ═ Data [ m ] -Data [ m-1] |/Δ t, m ═ 2,3, …, n of the absolute value relative to a Data acquisition time interval Δ t; and then carry on the detection of the outlier according to this, if the board surface of the ship board top strake of the target ship and deck is smooth, have xi ≦ epsilon, epsilon is a certain appropriate threshold, when xi > epsilon, the data point is judged as the outlier, namely the unusual data point, is abandoned;

s2, matching the point cloud preprocessing data frame with a reference data frame of a target ship in still water

Firstly, in order to match a point cloud preprocessing data frame with a target ship reference data frame in still water, the point cloud preprocessing data frame needs to rotate by taking a characteristic point M as a center and translate along an X axis and a Z axis, and the rotation angle is recorded as theta and the translation amount along the X axis is recorded as D_xAnd a translation amount along the Z axis of D_z. The maximum angle of the rotation of the point cloud preprocessing data frame in practice is theta_m，θ∈[-θ_m,θ_m]If the step size is b, go through the whole [ -theta ]_m,θ_m]The number of steps required for the interval is U to int (θ)_mB). When the rotation angle theta (i) is b X (i-U), the point cloud preprocessing data frame obtained by the histogram translation method needs to be respectively translated along the X axis and the Z axis by D_x(i) And D_z(i) Calculating a matching error (i) between the point cloud preprocessing data frame and a target ship reference data frame in still water, wherein i is 0,1,2,3, … and 2U;

then, searching the minimum value of the matching error between frames in error (i), and when i is equal to i_eminWhen the error is minimum, the matching error between frames is recorded as error_min(i_emin) When theta is equal to theta (i)_emin) Matching the point cloud preprocessing data frame with a target ship reference data frame in still water, and outputting X-axis translation displacement D_x＝D_x(i_emin) And Z-axis translational displacement D_z＝D_z(i_emin)。

S3, calculating the relative movement of the front end of the bridge body of the transfer trestle and the transfer point on the target ship

The distances between the two sides of the front end of the bridge body of the transfer trestle and the deck of the target ship measured by the first laser sensor and the second laser sensor are q respectively₁And q is₂And calculating the relative displacement D of the transfer trestle bridge front end and the transfer point on the target ship along the surging direction according to the sizes of the target ship and the boarding trestle bridge_Ty(ii) a According to the heave displacement, the sway displacement and the violence of the transfer trestle base along with the host ship measured by the position and attitude sensors of the 2D laser radar arranged on the host shipThe rocking angle is calculated, and the displacement D of the 2D laser radar along the host along the swaying direction due to wave disturbance is calculated_HxDisplacement in the heave direction D_Hz(ii) a Then the relative displacement S of the transfer trestle bridge body front end and the transfer point on the target ship along the swaying direction is obtained_x＝D_x-D_HxRelative displacement S along the surge direction_y＝D_TyRelative displacement S in the heave direction_z＝D_z-D_Hz。

A working method of a sea transfer trestle wave compensation control system comprises the following steps:

A. after the target ship and the host ship are leaned against the upper, an operator controls each hydraulic motor to drive the rotary mechanism, the pitching mechanism and the bridge body telescopic mechanism according to information provided by the transfer point monitoring device, so that the front end of the transfer trestle bridge body moves to a position right above the transfer point of the target ship and suitable for safe lap joint of the transfer trestle bridge body;

B. the operator starts the active compensation mode of the transfer trestle heave compensation control system. According to the relative displacement of the front end of the current transfer trestle body and a transfer point on a target ship along the swaying direction, the surging direction and the heaving direction obtained by the relative motion measuring unit and the heaving displacement, the swaying displacement and the swaying angle of the transfer trestle base along with the ship measured by the attitude sensor in real time, the expected rotation quantity of the first hydraulic motor, the expected rotation quantity of the second hydraulic motor and the expected rotation quantity of the third hydraulic motor are solved by the first kinematics inverse solution module; the three-freedom-degree compensation controller outputs control voltages of a first electro-hydraulic servo valve, a second electro-hydraulic servo valve and a third electro-hydraulic servo valve according to expected rotation quantity and actual rotation quantity, changes the opening of a valve, adjusts the flow of hydraulic oil of the three hydraulic motors to control the cooperative motion of the slewing mechanism, the pitching mechanism and the bridge body stretching mechanism, compensates disturbance of the swaying motion of two side boats to the offshore transfer trestle in real time, realizes that the front end of the transfer trestle bridge body follows the transfer point on a target boat, and provides guarantee for the safe lapping and fixing of the trestle bridge body at the transfer point;

C. after the transfer trestle bridge body is fixed at a transfer point on the target ship, an operator switches the transfer trestle wave compensation control system to a heave compensation mode. According to the expansion amount of the expansion mechanism measured by the third encoder in real time, the included angle gamma between the transfer trestle bridge body and the horizontal plane measured by the tilt angle sensor in real time, the pitch angle of the pitching mechanism measured by the fourth encoder in real time, and the expected safety angle gamma between the trestle bridge body and the horizontal plane_dThe second kinematics inverse solution module calculates the expected telescopic quantity of the hydraulic cylinder; according to the expected expansion amount and the actual expansion amount of the hydraulic cylinder measured by the stay wire displacement sensor in real time, the heave compensation controller outputs the control voltage of the fourth electro-hydraulic servo valve, changes the opening of the valve, adjusts the hydraulic oil flow of the hydraulic cylinder, controls the movement of the heave mechanism, and ensures that the trestle bridge body and the horizontal plane always keep an expected safety angle unchanged.

Furthermore, the relative displacement D of the front end of the bridge body of the transfer trestle and the transfer point on the target ship along the surging direction_TyThe calculation method of (2) is as follows:

the method comprises the steps that a TV is used for representing the posture of a target ship deck at the previous moment, T is used for representing the position of a transfer point on the target ship deck at the previous moment, the front end P of a transfer trestle bridge body is aligned with the transfer point T on the target ship along the Z-axis direction at the previous moment, when the target ship generates pitching motion, the posture of the target ship deck is changed into T ' V ', the transfer point on the target ship deck is changed into the T ' position, a first laser sensor laser beam is emitted to a point I on the target ship deck, a second laser sensor laser beam is emitted to a point J on the target ship deck, and the distances between two sides of the front end of the transfer trestle bridge body and the target ship deck, which are measured by the two points₁、q₂。

In Δ IKJ, angle IKJ is 90 °, | KJ | ═ q₂-q₁And w is the distance between the first laser sensor and the second laser sensor, and the target ship pitch angle calculation formula is as follows:

in Δ O 'TV, angle TVO' is 90 °, | TV | ═ D₃，|O′V|＝D₄Then, obtaining:

∠O′TV＝arctan(|O′V|/|TV)＝arctan(D₄/D₃)

in Δ O ' TT ', | O ' T | ═ O ' T ' |, given in combination formula (1):

∠T′TR＝(180°-ρ)/2-arctan(D₄/D₃)

in Δ TT 'R, the angle T' RT becomes 90 °, then:

further, the calculation method of the first inverse kinematics solution module is as follows:

according to the kinematics principle, a homogeneous transformation matrix of a trestle base coordinate system {0} relative to a geodetic coordinate system { G } is transformed as follows:

in the formula, S_heave、S_sway、δ_rHeave displacement, sway displacement and roll angle of the transfer trestle base along with the ship, S measured by the attitude sensor_surge、δ_p、δ_zThe transfer trestle base is respectively used for surging displacement, a surging angle and a bow angle along with the ship.

Because the host ship is provided with the dynamic positioning system, the influence of the swaying, surging and yawing motions of the host ship on the transfer trestle is ignored; and because the transfer trestle is arranged on the deck of the host ship and close to the target shipThe influence of the pitching motion of the host ship on the transfer trestle is ignored near the center of the side board on one side; thus, only the disturbances of the host vessel heave and roll motions on the transfer trestle need to be compensated, which only results in a heave displacement S of the transfer trestle base_heaveA swaying displacement S_swayAnd roll angle delta_rAnd S is_surge＝0，δ_p＝0，δ _z0, so the matrix is transformed in a homogeneous way

The method is simplified as follows:

the rotation matrix of the coordinate system {0} of the transfer trestle base relative to the coordinate system { G } of the ground is:

the coordinate of the point A at the position of the 2D laser radar in the coordinate system {0} of the transfer trestle base is (D)₁,D₂,h₁). Then the homogeneous transformation matrix of the 2D lidar coordinate system {1} relative to the transfer trestle base coordinate system {0} is:

then the homogeneous transformation matrix of the 2D lidar coordinate system {1} relative to the geodetic coordinate system { G } is:

therefore, the coordinates of the point A where the 2D laser radar is located in the geodetic coordinate system { G } are obtained as follows:

coordinates of a front end P point of the transfer trestle bridge body in a transfer trestle base coordinate system {0} are (Lsin (alpha) cos (beta) + acos (beta), Lsin (alpha) sin (beta) + asin (beta), -Lcos (alpha) + h), note:

the homogeneous transformation matrix of the coordinate system {2} at the front end of the transfer trestle body relative to the coordinate system {0} of the transfer trestle base is as follows:

in the formula (I), the compound is shown in the specification,

the method is characterized in that the method is a rotation matrix of a coordinate system {2} at the front end of a transfer trestle bridge body relative to a coordinate system {0} at the base of the transfer trestle, L is the current length of the transfer trestle bridge body, a is the radius of a transfer trestle boarding platform, alpha is the current pitch angle of a pitching mechanism, beta is the current rotation angle of a slewing mechanism, and h is the current height of a heaving mechanism. The homogeneous transformation matrix of the coordinate system {2} of the front end of the bridge body of the transfer trestle relative to the coordinate system { G } of the ground is:

and obtaining the coordinates of the front end P point of the transfer trestle bridge body in the geodetic coordinate system { G }:

when the operator switches the transfer trestle to the active compensation working mode, the height h of the heave mechanism of the transfer trestle₀Pitching angle alpha of pitching mechanism₀Rotation angle beta of the turning mechanism₀And transfer trestle base heave displacementS_heave0A swaying displacement S_sway0Roll angle delta_r0All the coordinates are obtained by a measuring system, and then the coordinate of the point A at the position of the 2D laser radar under the geodetic coordinate system { G } is known according to the formula (2)^GA₀＝[^GX_A0 ^GY_A0 ^GZ_A0]^TAccording to the formula (3), the coordinate of the front point P of the bridge body of the transfer trestle at the moment under the geodetic coordinate system { G }, is known^GP_tip0＝[^GX_tip0 ^GY_tip0 ^GZ_tip0]^TObtaining the displacement of the 2D laser radar along the heave direction as D_Hz＝^GZ_A-^GZ_A0A displacement in the yaw direction is D_Hx＝^GX_A-^GX_A0。

When the target ship and the host ship are leaned against the side, the two ships are connected together through the cable and the fender, the target ship is restrained by the cable and the fender, the swaying, surging and yawing motions are ignored, the heaving, swaying and pitching motions cause the transfer point on the deck of the target ship to follow up, and the relative displacement S of the front end of the bridge body of the transfer trestle and the transfer point on the target ship along the swaying direction_xRelative displacement S along the surge direction_yRelative displacement S in the heave direction_zRemember S_m＝[S_x S_y S_z]^T；^GP_{tip_d}＝[^GX_{tip_d} ^GY_{tip_d} ^GZ_{tip_d}]^TRepresenting the expected position of the front end P point of the transfer trestle bridge body in a geodetic coordinate system { G }; considering that the control target is to make the P point at the front end of the bridge body of the transfer trestle follow up with the transfer point on the target ship, the following steps are provided:

^GP_{tip_d}＝^GP_tip0+S_m (4)

the coordinate formula (3) of the point P at the front end of the transfer trestle bridge body under the geodetic coordinate system { G } is equal to the coordinate formula (4) of the expected position of the point P under the geodetic coordinate system { G }, and the expected rotation angle beta of the transfer trestle rotation mechanism is obtained by solving_d＝f₁(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) Desired pitch angle α of the pitch mechanism_d＝f₂(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) Desired length L of the telescopic mechanism_d＝f₃(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) The rotation angle of the rotary mechanism to be compensated is Δ β ═ β_d-β₀The pitch angle of the pitch mechanism to be compensated is delta alpha-alpha_d-α₀The expansion amount of the expansion mechanism needing to be compensated is delta L ═ L_d-L₀。

Obtaining the expected rotation quantity eta of the first hydraulic motor according to the specific structures of the slewing mechanism, the pitching mechanism and the bridge body telescopic mechanism₁K is the transmission ratio between the rotation angle of the slewing mechanism and the rotation quantity of the first hydraulic motor; desired rotation amount η of second hydraulic motor₂＝f₄(Δα)，f₄The (-) shows the transmission relation between the pitch angle of the pitch mechanism and the rotation quantity of the second hydraulic motor; desired rotation amount η of third hydraulic motor₃＝f₅(ΔL)，f₅And (c) shows the transmission relation between the telescopic amount of the telescopic mechanism and the rotation amount of the third hydraulic motor.

Further, the calculation method of the second inverse kinematics solution module is as follows:

let DP denote the attitude of the transfer trestle at the previous moment, and the expected angle between the transfer trestle and the horizontal plane is gamma_dThe front end P of the transfer trestle bridge body is fixedly connected with a transfer point on a target ship, and when the host ship and the target ship generate disturbance to the transfer trestle due to swinging motion, the posture of the transfer trestle bridge body is changed into DP', so as to ensure that the transfer trestle bridge body keeps a desired angle gamma with the horizontal plane_dAnd (4) actively controlling the heave mechanism to stretch without changing, so that the posture of the transfer trestle bridge body is changed into D 'P'.

In Δ DD 'P', we derive from the sine theorem:

in the formula, | DP '| is L, L is the current length of the transfer trestle bridge body, | DD' | Δ h, and Δ h is the telescopic displacement of the heave mechanism.

When gamma is less than or equal to gamma_dWhen the angle D 'P' D is equal to gamma_d- γ and ═ P' D ═ α - (γ)_d- γ), according to equation (5), the telescopic displacement of the heave mechanism

Obtaining the expected expansion amount delta X of the hydraulic cylinder as delta h according to the specific structure of the heave mechanism;

when gamma > gamma_dWhen the angle D 'P' D is equal to gamma-gamma_d，∠P′D′D＝180°-[α+(γ-γ_d)]According to the formula (5), the telescopic displacement of the heave mechanism

According to the specific structure of the heave mechanism, the expected expansion and contraction quantity delta X of the hydraulic cylinder is obtained as minus delta h.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the relative movement measuring unit comprising the 2D laser radar obtains the relative displacement between the front end of the transfer trestle bridge body after the leaning on and the transfer point on the target ship, so that the follow-up control of the front end of the transfer trestle bridge body and the transfer point on the target ship is conveniently realized, particularly, the target ship is not required to be provided with the movement reference unit MRU, and the cost is reduced.

2. The invention adopts a time sequence method to forecast the movement of the transfer trestle base along with the ship and the relative displacement of the transfer trestle body front end and the transfer point on the target ship in an extremely short period, further adopts an active disturbance rejection control technology to realize the cooperative motion synchronous control of the hydraulic actuating mechanism of the transfer trestle, actively and synchronously compensates the disturbance of the ship swaying movement caused by waves to the transfer trestle, and can ensure that a control system obtains stronger anti-jamming capability and higher control precision.

3. The invention considers the physical limitations of the transfer trestle swing mechanism, the pitching mechanism, the bridge body stretching mechanism and the heaving mechanism, adopts the motion amplitude limiting module to reasonably plan the motion tracks of the motion mechanisms and generate control instruction signals of each hydraulic actuating mechanism meeting the constraint conditions of displacement, speed and acceleration of each motion mechanism, so that the motion states of the motion mechanisms do not exceed the motion state limit value of the motion mechanisms, and the mechanisms can move smoothly, thereby avoiding the vibration of the transfer trestle and prolonging the service life.

4. After the transfer trestle is fixed with the transfer point on the target ship, the safe angle between the trestle body and the horizontal plane can be kept unchanged only by controlling the heaving mechanism, the control is easy, the energy is saved, and the safety and the comfort of personnel transfer between two ships on the sea are ensured.

Drawings

Fig. 1 is a schematic working diagram of a transfer trestle of the invention.

Fig. 2 is a schematic structural diagram of a transfer trestle according to the present invention.

Fig. 3 is a schematic diagram of a work flow of the three-degree-of-freedom compensation controller of the transfer trestle of the present invention.

Fig. 4 is a schematic diagram of the work flow of the heave compensation controller of the transfer trestle of the invention.

Fig. 5 is a schematic view of the working principle of the relative movement measuring unit of the present invention.

Fig. 6 is a partially enlarged view of the region E of fig. 5.

Fig. 7 is a geometrical relationship diagram of the front end of the bridge body of the transfer trestle and the transfer point on the deck of the target ship.

Fig. 8 is a side view of a transfer trestle with a coordinate system for a first inverse kinematics solution.

Fig. 9 is a top view of a transfer trestle with a coordinate system for a first inverse kinematics solution.

Fig. 10 is a side view of a transfer trestle with a coordinate system for a second inverse kinematics solution.

FIG. 11 shows the case where γ in FIG. 10 is ≦ γ_dAnd then, transferring a geometric relation graph of each mechanism of the trestle.

FIG. 12 shows the case where γ > γ in FIG. 10_dAnd then, transferring a geometric relation graph of each mechanism of the trestle.

FIG. 13 is a flow chart of a relative motion measurement unit operating scheme of the present invention.

In the figure: 1. a control box, 2D laser radar, 3, PLC, 4, a main control computer, 5, a transfer trestle base, 6, a hydraulic cylinder, 7, a heave mechanism, 8, a first hydraulic motor, 9, a swing mechanism, 10, a boarding platform, 11, a second hydraulic motor, 12, a pitching mechanism, 13, a third hydraulic motor, 14, a bridge body expansion mechanism, 15, a transfer point monitoring device, 16, a first encoder, 17, a second encoder, 18, a third encoder, 19, a stay wire displacement sensor, 20, a fourth encoder, 21, an inclination angle sensor, 22, an attitude sensor, 23, a relative motion measuring unit, 24, a first electro-hydraulic servo valve, 25, a second electro-hydraulic servo valve, 26, a third electro-hydraulic servo valve, 27, a fourth electro-hydraulic servo valve, 28, a filter, 29, a host ship motion forecasting module, 30, a relative motion forecasting module, 31 and a first motion forecasting module, 32. the device comprises a first kinematic inverse solution module 33, a three-degree-of-freedom compensation controller 34, a second kinematic amplitude limiting module 35, a second kinematic inverse solution module 36, a heave compensation controller 37, a first laser sensor 38 and a second laser sensor.

Detailed Description

The invention is further described below with reference to the accompanying drawings. As shown in fig. 1-13, the sea transfer trestle wave compensation control system comprises a heave mechanism 7, a swing mechanism 9, a pitch mechanism 12 and a bridge body telescopic mechanism 14, and the wave compensation control system comprises a hydraulic execution mechanism, a measurement system, an electro-hydraulic servo valve, a wave compensation control unit, a control box 1, a PLC3 and a main control computer 4.

The hydraulic actuating mechanism comprises a hydraulic cylinder 6, a first hydraulic motor 8, a second hydraulic motor 11 and a third hydraulic motor 13, wherein the hydraulic cylinder 6 is used for driving a heave mechanism 7 of the transfer trestle to stretch, the first hydraulic motor 8 is used for driving a swing mechanism 9 of the transfer trestle to rotate, the second hydraulic motor 11 is used for driving a pitching mechanism 12 of the transfer trestle to pitch, and the third hydraulic motor 13 is used for driving a bridge body stretching mechanism 14 of the transfer trestle to stretch;

the measuring system comprises a first encoder 16, a second encoder 17, a third encoder 18, a stay wire displacement sensor 19, a fourth encoder 20, an inclination angle sensor 21, an attitude sensor 22, a 2D laser radar 2, a transfer point monitoring device 15 and a relative movement measuring unit 23, wherein the first encoder 16 is arranged on the first hydraulic motor 8 and is used for measuring the rotation quantity of the first hydraulic motor 8 and obtaining the rotation angle of the slewing mechanism 9; the second encoder 17 is mounted on the second hydraulic motor 11 and is used for measuring the rotation quantity of the second hydraulic motor 11; the third encoder 18 is mounted on the third hydraulic motor 13 and is used for measuring the rotation quantity of the third hydraulic motor 13 and obtaining the expansion and contraction quantity of the bridge expansion and contraction mechanism 14; the stay wire displacement sensor 19 is arranged on the hydraulic cylinder 6 and used for measuring the displacement of the heave mechanism 7; the fourth encoder 20 is used for measuring the pitch angle of the pitch mechanism 12; the inclination angle sensor 21 is mounted on the transfer trestle bridge body and used for measuring an included angle formed by the transfer trestle bridge body and a horizontal plane; the attitude sensor 22 is arranged at the geometric center of the transfer trestle base 5 on the host ship and is used for measuring the heave displacement, the sway displacement and the roll angle of the transfer trestle base 5 along with the ship; the 2D laser radar 2 is arranged on a deck near a side board of the host ship close to one side of the target ship and is used for scanning a topside strake and a deck area of the target ship to obtain a point cloud data frame containing geometric shape information of a scanned area; the transfer point monitoring device 15 is arranged at the front end of the bridge body of the transfer trestle and comprises a camera and a laser sensor; the camera shoots the area where the transfer point on the target ship is located and is used for monitoring the transfer point on the target ship; the laser sensors comprise a first laser sensor 37 and a second laser sensor 38 which are respectively arranged on two sides of the front end of the transfer trestle bridge body and used for measuring the distance between the two sides of the front end of the transfer trestle bridge body and the deck of the target ship; the relative motion measuring unit 23 is configured to obtain a relative displacement between the front end of the transfer trestle bridge and a transfer point on the target ship;

the electro-hydraulic servo valves comprise a plurality of first electro-hydraulic servo valves 24, second electro-hydraulic servo valves 25, third electro-hydraulic servo valves 26 and fourth electro-hydraulic servo valves 27, wherein the first electro-hydraulic servo valves 24, the second electro-hydraulic servo valves 25, the third electro-hydraulic servo valves 26 and the fourth electro-hydraulic servo valves 27 are respectively used for controlling the hydraulic oil flow of the first hydraulic motor 8, the second hydraulic motor 11, the third hydraulic motor 13 and the hydraulic cylinder 6;

the heave compensation control unit comprises a filter 28, a host ship motion forecast module 29, a relative motion forecast module 30, a first motion amplitude limiting module 31, a first kinematic inverse solution module 32, a three-degree-of-freedom compensation controller 33, a second motion amplitude limiting module 34, a second kinematic inverse solution module 35 and a heave compensation controller 36;

the filter 28 receives the expansion amount of the bridge expansion mechanism 14 measured by the third encoder 18, the included angle between the transfer trestle bridge and the horizontal plane measured by the tilt sensor 21, the pitch angle of the pitch mechanism 12 measured by the fourth encoder 20, and the heave displacement, the roll displacement and the roll angle of the transfer trestle base 5 along with the ship measured by the attitude sensor 22, and outputs the filter value of the received information;

the host ship motion forecasting module 29 receives the filter value from the filter 28, applies a time series method to forecast the heaving displacement, swaying displacement and swaying angle of the transfer trestle base 5 along with the ship in an extremely short period, and outputs forecast values of the heaving displacement, swaying displacement and swaying angle of the transfer trestle base 5 along with the ship at the next control moment;

the relative motion prediction module 30 receives the relative displacement of the front end of the transfer trestle bridge body from the relative motion measurement unit 23 and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction, applies a time sequence method to carry out extremely short-term prediction on the relative displacement of the front end of the transfer trestle bridge body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction, and outputs a prediction value of the relative displacement of the front end of the transfer trestle bridge body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction at the next control moment;

the first motion amplitude limiting module 31 receives the predicted values from the host ship motion prediction module 29 and the relative motion prediction module 30, plans the motion tracks of the slewing mechanism 9, the pitching mechanism 12 and the bridge body stretching mechanism 14 according to the constraint conditions of displacement, speed and acceleration caused by the physical limitations of the slewing mechanism 9, the pitching mechanism 12 and the bridge body stretching mechanism 14, and generates three hydraulic motor control instruction signals meeting the motion constraint conditions of the slewing mechanism 9, the pitching mechanism 12 and the bridge body stretching mechanism 14;

the first kinematic inverse solution module 32 receives the three hydraulic motor control instruction signals generated by the first motion amplitude limiting module 31, and calculates the respective expected rotation amounts of the three hydraulic motors;

the three-degree-of-freedom compensation controller 33 receives the expected rotation amounts of the three hydraulic motors from the first kinematic inverse solution module 32, and obtains the control voltages corresponding to the first electro-hydraulic servo valve 24, the second electro-hydraulic servo valve 25 and the third electro-hydraulic servo valve 26, which are required by the expected rotation amounts of the hydraulic motors, through a three-degree-of-freedom active disturbance rejection compensation control law; the working mode of the three-degree-of-freedom compensation controller 33 is called as an active compensation mode;

the second motion amplitude limiting module 34 receives the filter values of the expansion amount of the bridge expansion mechanism 14 from the filter 28, the included angle formed by the bridge body of the transfer trestle and the horizontal plane and the pitch angle of the pitching mechanism 12, plans the motion trail of the heave mechanism 7 according to the constraint conditions of displacement, speed and acceleration caused by the physical limitation of the heave mechanism 7, and generates a hydraulic cylinder 6 control instruction signal meeting the motion constraint conditions of the heave mechanism 7;

the second kinematic inverse solution module 35 receives a hydraulic cylinder 6 control instruction signal from the second motion amplitude limiting module 34, and calculates an expected telescopic amount of the hydraulic cylinder 6 according to a control target of the transfer trestle, that is, a certain safe angle is always kept between a bridge body of the transfer trestle and a horizontal plane;

the heave compensation controller 36 receives the expected expansion amount of the hydraulic cylinder 6 from the second kinematic inverse solution module 35, and obtains the control voltage of the fourth electro-hydraulic servo valve 27 required by the expected expansion amount of the hydraulic cylinder 6 through an auto-disturbance-rejection heave compensation control law; the operating mode of heave compensation controller 36 is referred to as heave compensation mode;

the control box 1 is arranged on a deck of a host ship; the PLC3 is installed in the control box 1 and is used for realizing the functions of the filter 28, the first motion amplitude limiting module 31, the three-degree-of-freedom compensation controller 33, the second motion amplitude limiting module 34 and the heave compensation controller 36; the main control computer 4 is installed in the control box 1 and is used for realizing the functions of the first kinematics inverse solution module 32, the second kinematics inverse solution module 35, the relative motion measurement unit 23, the host ship motion forecast module 29 and the relative motion forecast module 30.

Further, the area scanned by the 2D lidar 2 always includes the feature point M on the target ship, and the point cloud data frame obtained by the 2D lidar 2 is composed of N distance data, and the obtained point cloud data frame is sent to the main control computer 4.

Further, the filter 28 is a low-pass filter for filtering out high-frequency signals contained in the measurement signal of the attitude sensor 22 and the measurement signal of the tilt sensor 21, which are caused by high-frequency deck vibration caused by operations of equipment such as a marine main engine.

Further, the working method of the relative movement measuring unit 23 includes the following steps:

s1, preprocessing the point cloud data frame obtained by the 2D laser radar 2

Firstly, intercepting each frame of point cloud data from within a 2D laser radar 2 scanning angle psi to obtain a point cloud data frame consisting of N distance data, wherein N is less than N; then, calculating an absolute value | Data [ m ] -Data [ m-1] | of the difference between the mth distance Data and the mth-1 distance Data in each frame of point cloud Data, and calculating a change rate ξ ═ Data [ m ] -Data [ m-1] |/Δ t, m ═ 2,3, …, n of the absolute value relative to a Data acquisition time interval Δ t; and then carry on the detection of the outlier according to this, if the board surface of the ship board top strake of the target ship and deck is smooth, have xi ≦ epsilon, epsilon is a certain appropriate threshold, when xi > epsilon, the data point is judged as the outlier, namely the unusual data point, is abandoned;

First, to preprocess the point cloudThe data frame is matched with a reference data frame of a target ship in still water, the point cloud preprocessing data frame needs to rotate by taking the characteristic point M as a center and translate along an X axis and a Z axis, the rotation angle is recorded as theta, and the translation amount along the X axis is recorded as D_xAnd a translation amount along the Z axis of D_z. The maximum angle of the rotation of the point cloud preprocessing data frame in practice is theta_m，θ∈[-θ_m,θ_m]If the step size is b, go through the whole [ -theta ]_m,θ_m]The number of steps required for the interval is U to int (θ)_mB). When the rotation angle theta (i) is b X (i-U), the point cloud preprocessing data frame obtained by the histogram translation method needs to be respectively translated along the X axis and the Z axis by D_x(i) And D_z(i) Calculating a matching error (i) between the point cloud preprocessing data frame and a target ship reference data frame in still water, wherein i is 0,1,2,3, … and 2U;

The distances from both sides of the front end of the bridge body of the transfer trestle to the deck of the target ship measured by the first laser sensor 37 and the second laser sensor 38 are q respectively₁And q is₂And calculating the relative displacement D of the transfer trestle bridge front end and the transfer point on the target ship along the surging direction according to the sizes of the target ship and the boarding trestle bridge_Ty(ii) a According to the heave displacement, the sway displacement and the roll angle of the transfer trestle base 5 along with the host, which are measured by the position of the 2D laser radar 2 arranged on the host ship and the attitude sensor 22, the displacement D of the 2D laser radar 2 along with the host along the sway direction is calculated through wave disturbance_HxDisplacement in the heave direction D_Hz(ii) a Then the relative displacement S of the transfer trestle bridge body front end and the transfer point on the target ship along the swaying direction is obtained_x＝D_x-D_HxRelative displacement S along the surge direction_y＝D_TyRelative displacement S in the heave direction_z＝D_z-D_Hz。

A. after the target ship leans against the host ship, an operator controls each hydraulic motor to drive the rotating mechanism 9, the pitching mechanism 12 and the bridge body telescopic mechanism 14 according to information provided by the transfer point monitoring device 15, so that the front end of the bridge body of the transfer trestle moves to a position right above the transfer point of the target ship and suitable for safe lap joint of the bridge body of the transfer trestle;

B. the operator starts the active compensation mode of the transfer trestle heave compensation control system. According to the relative displacement of the front end of the current transfer trestle body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction obtained by the relative motion measuring unit 23 and the heaving displacement, the swaying displacement and the swaying angle of the transfer trestle base 5 along with the ship measured by the attitude sensor 22 in real time, the first kinematics inverse solution module 32 is used for solving the expected rotation quantity of the first hydraulic motor 8, the expected rotation quantity of the second hydraulic motor 11 and the expected rotation quantity of the third hydraulic motor 13; the first encoder 16, the second encoder 17 and the third encoder 18 respectively feed back the actual rotation quantity of the first hydraulic motor 8, the actual rotation quantity of the second hydraulic motor 11 and the actual rotation quantity of the third hydraulic motor 13 in real time, the three-degree-of-freedom compensation controller 33 outputs control voltages of the first electro-hydraulic servo valve 24, the second electro-hydraulic servo valve 25 and the third electro-hydraulic servo valve 26 according to the expected rotation quantity and the actual rotation quantity, the valve opening degree is changed, the flow rates of hydraulic oil of the three hydraulic motors are adjusted, the swing mechanism 9, the pitching mechanism 12 and the bridge body telescopic mechanism 14 are controlled to move cooperatively, the disturbance of the swaying motion of two alongside ships on the offshore transfer trestle is compensated in real time, the transfer trestle bridge front end is realized to follow up with a transfer point on a target ship, and guarantee is provided for safe overlapping and fixing of the trestle bridge at the transfer point;

C. after the transfer trestle bridge body is fixed at a transfer point on the target ship, an operator switches the transfer trestle wave compensation control system to a heave compensation mode. According to the third codeThe stretching amount of the stretching mechanism measured by the device 18 in real time, the included angle gamma between the bridge body of the transfer trestle and the horizontal plane measured by the tilt angle sensor 21 in real time, the pitch angle of the pitching mechanism 12 measured by the fourth encoder 20 in real time, and the expected safety angle gamma between the bridge body of the transfer trestle and the horizontal plane_dThe second inverse kinematics module 35 calculates the expected telescopic amount of the hydraulic cylinder 6; according to the expected expansion amount and the actual expansion amount of the hydraulic cylinder 6 measured by the stay wire displacement sensor 19 in real time, the heave compensation controller 36 outputs the control voltage of the fourth electro-hydraulic servo valve 27, changes the valve opening, and adjusts the hydraulic oil flow of the hydraulic cylinder 6 to control the movement of the heave mechanism 7, so as to ensure that the trestle bridge body and the horizontal plane always keep an expected safety angle unchanged.

let TV show the attitude of the target ship's deck at the previous moment, T show the position of the transfer point on the target ship's deck at the previous moment, the front end P of the transfer trestle bridge body is aligned with the transfer point T on the target ship along the Z-axis direction at the previous moment, when the target ship generates pitching motion, the attitude of the target ship's deck is changed into T ' V ', the transfer point on the attitude is changed into T ' position, the first laser sensor 37 laser beam is irradiated on the I point on the target ship's deck, the second laser sensor 38 laser beam is irradiated on the J point on the target ship's deck, the distances measured by the two from the two sides of the front end of the transfer trestle bridge body to the target ship's deck are q respectively₁、q₂。

In Δ IKJ, angle IKJ is 90 °, | KJ | ═ q₂-q₁If w is the distance between the first laser sensor 37 and the second laser sensor 38, the pitch angle of the target ship is calculated as follows:

∠O′TV＝arctan(|O′V|/|TV)＝arctan(D₄/D₃)

in Δ O ' TT ', | O ' T | ═ O ' T ' |, given in combination formula (1):

∠T′TR＝(180°-ρ)/2-arctan(D₄/D₃)

in Δ TT 'R, the angle T' RT becomes 90 °, then:

further, the calculation method of the first inverse kinematics solution module 32 is as follows:

according to the kinematics principle, a homogeneous transformation matrix of a coordinate system {0} of the trestle base 5 relative to a geodetic coordinate system { G } is:

in the formula, S_heave、S_sway、δ_rRespectively, the heave displacement, the sway displacement and the roll angle S of the transfer trestle base 5 along with the ship, which are measured by the attitude sensor 22_surge、δ_p、δ_zThe transfer trestle base 5 is respectively provided with the longitudinal swing displacement, the longitudinal rocking angle and the fore rocking angle along with the ship.

Because the host ship is provided with the dynamic positioning system, the influence of the swaying, surging and yawing motions of the host ship on the transfer trestle is ignored; the transfer trestle is arranged near the center of the side board of the host ship deck close to the target ship, so that the influence of the pitching motion of the host ship on the transfer trestle is ignored; thus, only the disturbances caused by the heave and roll motions of the host vessel on the transfer trestle need to be compensated, which only results in transfersThe landing stage base 5 generates heave displacement S_heaveA swaying displacement S_swayAnd roll angle delta_rAnd S is_surge＝0，δ_p＝0，δ _z0, so the matrix is transformed in a homogeneous way

The method is simplified as follows:

the rotation matrix of the coordinate system {0} of the transfer trestle base 5 relative to the geodetic coordinate system { G } is:

the coordinate of the point A at the position of the 2D laser radar 2 in the coordinate system {0} of the transfer trestle base 5 is (D)₁,D₂,h₁). The homogeneous transformation matrix of the 2D lidar 2 coordinate system {1} relative to the transformation trestle base 5 coordinate system {0} is:

then the homogeneous transformation matrix of the 2D lidar 2 coordinate system {1} with respect to the geodetic coordinate system { G } is:

therefore, the coordinates of the point a at the position of the 2D lidar 2 in the geodetic coordinate system { G } are:

coordinates of a front end P point of the transfer trestle bridge body in a coordinate system {0} of the transfer trestle base 5 are (Lsin (alpha) cos (beta) + acos (beta), Lsin (alpha) sin (beta) + asin (beta), -Lcos (alpha) + h), note:

the homogeneous transformation matrix of the coordinate system {2} at the front end of the transfer trestle bridge body relative to the coordinate system {0} of the transfer trestle base 5 is as follows:

in the formula (I), the compound is shown in the specification,

the transfer matrix is a rotation matrix of a coordinate system {2} at the front end of the transfer trestle bridge body relative to a coordinate system {0} of a transfer trestle base 5, L is the current length of the transfer trestle bridge body, a is the radius of the transfer trestle boarding platform 10, alpha is the current pitch angle of the pitching mechanism 12, beta is the current rotation angle of the slewing mechanism 9, and h is the current height of the heaving mechanism 7. The homogeneous transformation matrix of the coordinate system {2} of the front end of the bridge body of the transfer trestle relative to the coordinate system { G } of the ground is:

when the operator switches the transfer trestle to the active compensation working mode, the height h of the heave mechanism 7 of the transfer trestle ₀12 pitch angle alpha of pitch mechanism₀Rotation angle beta of the turning mechanism 9₀And the transfer trestle base 5 is subjected to heave displacement S_heave0A swaying displacement S_sway0Roll angle delta_r0All the data are obtained by a measuring system, and then the coordinates of the point A at the position of the 2D laser radar 2 on the earth are known according to the formula (2)Coordinates under the system { G }^GA₀＝[^GX_A0 ^GY_A0 ^GZ_A0]^TAccording to the formula (3), the coordinate of the front point P of the bridge body of the transfer trestle at the moment under the geodetic coordinate system { G }, is known^GP_tip0＝[^GX_tip0 ^GY_tip0 ^GZ_tip0]^TObtaining the displacement of the 2D laser radar 2 along the heave direction as D_Hz＝^GZ_A-^GZ_A0A displacement in the yaw direction is D_Hx＝^GX_A-^GX_A0。

^GP_{tip_d}＝^GP_tip0+S_m (4)

the coordinate formula (3) of the point P at the front end of the transfer trestle bridge body under the geodetic coordinate system { G } is equal to the coordinate formula (4) of the expected position of the point P under the geodetic coordinate system { G }, and the expected rotation angle beta of the transfer trestle rotation mechanism 9 is obtained by solving_d＝f₁(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) Desired pitch angle α of pitch mechanism 12_d＝f₂(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) Stretching and drawing deviceDesired length L of the contraction mechanism_d＝f₃(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) The rotation angle to be compensated for by the turning mechanism 9 is Δ β ═ β_d-β₀The pitch angle of the pitch mechanism 12 to be compensated is Δ α ═ α_d-α₀The expansion amount of the expansion mechanism needing to be compensated is delta L ═ L_d-L₀。

The expected rotation amount eta of the first hydraulic motor 8 is obtained according to the specific structures of the slewing mechanism 9, the pitching mechanism 12 and the bridge body stretching mechanism 14₁K Δ β, k is a transmission ratio between the rotation angle of the turning mechanism 9 and the rotation amount of the first hydraulic motor 8; desired rotation amount η of the second hydraulic motor 11₂＝f₄(Δα)，f₄(. cndot.) represents the transmission relationship between the pitch angle of the pitch mechanism 12 and the rotation amount of the second hydraulic motor 11; desired rotation amount η of the third hydraulic motor 13₃＝f₅(ΔL)，f₅And (c) represents the transmission relationship between the expansion and contraction amount of the expansion and contraction mechanism and the rotation amount of the third hydraulic motor 13.

Further, the calculation method of the second inverse kinematics solution module 35 is as follows:

let DP denote the attitude of the transfer trestle at the previous moment, and the expected angle between the transfer trestle and the horizontal plane is gamma_dThe front end P of the transfer trestle bridge body is fixedly connected with a transfer point on a target ship, and when the host ship and the target ship generate disturbance to the transfer trestle due to swinging motion, the posture of the transfer trestle bridge body is changed into DP', so as to ensure that the transfer trestle bridge body keeps a desired angle gamma with the horizontal plane_dAnd (4) actively controlling the heave mechanism 7 to stretch without changing, so that the posture of the transfer trestle bridge body is changed into D 'P'.

In Δ DD 'P', we derive from the sine theorem:

in the formula, | DP '| is L, L is the current length of the transfer trestle bridge body, | DD' | Δ h, and Δ h is the telescopic displacement of the heave mechanism (7).

When gamma is less than or equal to gamma_dWhen the angle D 'P' D is equal to gamma_d- γ and ═ P' D ═ α - (γ)_d- γ), as shown in equation (5), the telescopic displacement of the heave mechanism 7

According to the specific structure of the heave mechanism 7, obtaining the expected expansion amount delta X of the hydraulic cylinder 6 as delta h;

when gamma > gamma_dWhen the angle D 'P' D is equal to gamma-gamma_d，∠P′D′D＝180°-[α+(γ-γ_d)]According to the formula (5), the telescopic displacement of the heave mechanism 7

According to the specific structure of the heave mechanism 7, the desired amount Δ X of extension and retraction of the hydraulic cylinder 6 is obtained as- Δ h.

The present invention is not limited to the embodiment, and any equivalent idea or change within the technical scope of the present invention is to be regarded as the protection scope of the present invention.

Claims

1. The utility model provides an offshore transfer trestle wave compensation control system, offshore transfer trestle including heave mechanism (7), rotation mechanism (9), every single move mechanism (12) and bridge body telescopic machanism (14), its characterized in that: the wave compensation control system comprises a hydraulic actuating mechanism, a measuring system, an electro-hydraulic servo valve, a wave compensation control unit, a control box (1), a PLC (3) and a main control computer (4);

the hydraulic actuator comprises a hydraulic cylinder (6), a first hydraulic motor (8), a second hydraulic motor (11) and a third hydraulic motor (13), wherein the hydraulic cylinder (6) is used for driving a heave mechanism (7) of the transfer trestle to stretch, the first hydraulic motor (8) is used for driving a swing mechanism (9) of the transfer trestle to rotate, the second hydraulic motor (11) is used for driving a pitching mechanism (12) of the transfer trestle to pitch, and the third hydraulic motor (13) is used for driving a bridge body stretching mechanism (14) of the transfer trestle to stretch;

the measuring system comprises a first encoder (16), a second encoder (17), a third encoder (18), a stay wire displacement sensor (19), a fourth encoder (20), an inclination angle sensor (21), an attitude sensor (22), a 2D laser radar (2), a transfer point monitoring device (15) and a relative movement measuring unit (23), wherein the first encoder (16) is installed on a first hydraulic motor (8) and used for measuring the rotation quantity of the first hydraulic motor (8) and obtaining the rotation angle of a slewing mechanism (9); the second encoder (17) is arranged on the second hydraulic motor (11) and is used for measuring the rotation quantity of the second hydraulic motor (11); the third encoder (18) is arranged on the third hydraulic motor (13) and is used for measuring the rotation quantity of the third hydraulic motor (13) and obtaining the expansion and contraction quantity of the bridge expansion and contraction mechanism (14); the stay wire displacement sensor (19) is arranged on the hydraulic cylinder (6) and is used for measuring the displacement of the heave mechanism (7); the fourth encoder (20) is used for measuring the pitch angle of the pitch mechanism (12); the inclination angle sensor (21) is arranged on the transfer trestle bridge body and is used for measuring an included angle formed by the transfer trestle bridge body and a horizontal plane; the attitude sensor (22) is arranged at the geometric center of the transfer trestle base (5) on the host ship and is used for measuring the heave displacement, the sway displacement and the roll angle of the transfer trestle base (5) along with the ship; the 2D laser radar (2) is arranged on a deck near a side board of a host ship close to one side of a target ship and is used for scanning a board top strake and a deck area of the target ship to obtain a point cloud data frame containing geometric shape information of a scanned area; the transfer point monitoring device (15) is arranged at the front end of the bridge body of the transfer trestle and comprises a camera and a laser sensor; the camera shoots the area where the transfer point on the target ship is located and is used for monitoring the transfer point on the target ship; the laser sensors comprise a first laser sensor (37) and a second laser sensor (38), which are respectively arranged on two sides of the front end of the transfer trestle bridge body and are used for measuring the distance between the two sides of the front end of the transfer trestle bridge body and a target ship deck; the relative motion measuring unit (23) is used for obtaining the relative displacement between the front end of the transfer trestle bridge body and a transfer point on the target ship;

the electro-hydraulic servo valves comprise a plurality of first electro-hydraulic servo valves (24), a plurality of second electro-hydraulic servo valves (25), a plurality of third electro-hydraulic servo valves (26) and a plurality of fourth electro-hydraulic servo valves (27), wherein the first electro-hydraulic servo valves (24), the second electro-hydraulic servo valves (25), the third electro-hydraulic servo valves (26) and the fourth electro-hydraulic servo valves (27) are respectively used for controlling the hydraulic oil flow of the first hydraulic motor (8), the second hydraulic motor (11), the third hydraulic motor (13) and the hydraulic cylinder (6);

the wave compensation control unit comprises a filter (28), a host ship motion forecast module (29), a relative motion forecast module (30), a first motion amplitude limiting module (31), a first kinematic inverse solution module (32), a three-degree-of-freedom compensation controller (33), a second motion amplitude limiting module (34), a second kinematic inverse solution module (35) and a heave compensation controller (36);

the filter (28) receives the stretching amount of the bridge stretching mechanism (14) measured by the third encoder (18), the included angle between the transfer trestle bridge and the horizontal plane measured by the tilt angle sensor (21), the pitch angle of the pitch mechanism (12) measured by the fourth encoder (20), and the heave displacement, the roll displacement and the roll angle of the transfer trestle base (5) along with the ship measured by the attitude sensor (22), and outputs the filter value of the received information;

the host ship motion forecasting module (29) receives the filter value from the filter (28), applies a time sequence method to carry out extremely short-term forecasting on the heave displacement, the sway displacement and the roll angle of the transfer trestle base (5) along with the ship, and outputs forecasting values of the heave displacement, the sway displacement and the roll angle of the transfer trestle base (5) along with the ship at the next control moment;

the relative motion prediction module (30) receives the relative displacement of the front end of the transfer trestle body from the relative motion measurement unit (23) and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction, carries out extremely short-term prediction on the relative displacement of the front end of the transfer trestle body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction by applying a time sequence method, and outputs a prediction value of the relative displacement of the front end of the transfer trestle body and the transfer point on the target ship along the swaying direction, the surging direction and the heaving direction at the next control moment;

the first motion amplitude limiting module (31) receives predicted values from the host ship motion forecasting module (29) and the relative motion forecasting module (30), plans motion tracks of the slewing mechanism (9), the pitching mechanism (12) and the bridge body telescopic mechanism (14) according to displacement, speed and acceleration constraint conditions caused by physical limitations of the slewing mechanism (9), the pitching mechanism (12) and the bridge body telescopic mechanism (14), and generates three hydraulic motor control instruction signals meeting the motion constraint conditions of the slewing mechanism (9), the pitching mechanism (12) and the bridge body telescopic mechanism (14);

the first kinematic inverse solution module (32) receives the three hydraulic motor control command signals generated by the first kinematic amplitude limiting module (31) and solves the respective expected rotation amounts of the three hydraulic motors;

the three-degree-of-freedom compensation controller (33) receives the expected rotation quantity of each of the three hydraulic motors from the first kinematic inverse solution module (32), and obtains control voltages of the corresponding first electro-hydraulic servo valve (24), the second electro-hydraulic servo valve (25) and the third electro-hydraulic servo valve (26) required by the expected rotation quantity of each hydraulic motor through a three-degree-of-freedom active disturbance rejection compensation control law; the working mode of the three-degree-of-freedom compensation controller (33) is called as an active compensation mode;

the second motion amplitude limiting module (34) receives the stretching amount of the bridge body stretching mechanism (14) from the filter (28), the included angle formed by the bridge body of the transfer trestle and the horizontal plane and the filtering value of the pitch angle of the pitching mechanism (12), plans the motion track of the heave mechanism (7) according to the constraint conditions of displacement, speed and acceleration caused by the physical limitation of the heave mechanism (7), and generates a hydraulic cylinder (6) control instruction signal meeting the motion constraint conditions of the heave mechanism (7);

the second kinematic inverse solution module (35) receives a hydraulic cylinder (6) control instruction signal from the second kinematic amplitude limiting module (34), and calculates the expected telescopic amount of the hydraulic cylinder (6) according to a control target of the transfer trestle, namely, the transfer trestle body and the horizontal plane always keep a certain safe angle;

the heave compensation controller (36) receives the expected expansion and contraction quantity of the hydraulic cylinder (6) from the second kinematic inverse solution module (35), and obtains the control voltage of a fourth electro-hydraulic servo valve (27) required by the expected expansion and contraction quantity of the hydraulic cylinder (6) through an auto-disturbance rejection heave compensation control law; the working mode of the heave compensation controller (36) is called a heave compensation mode;

the control box (1) is arranged on a deck of a host ship; the PLC (3) is arranged in the control box (1) and is used for realizing the functions of the filter (28), the first motion amplitude limiting module (31), the three-degree-of-freedom compensation controller (33), the second motion amplitude limiting module (34) and the heave compensation controller (36); the main control computer (4) is arranged in the control box (1) and is used for realizing the functions of the first kinematics inverse solution module (32), the second kinematics inverse solution module (35), the relative motion measurement unit (23), the host ship motion forecast module (29) and the relative motion forecast module (30).

2. The offshore transfer trestle wave compensation control system of claim 1, wherein: the area scanned by the 2D laser radar (2) always comprises the characteristic point M on the target ship, the point cloud data frame obtained by the 2D laser radar (2) is composed of N distance data, and the obtained point cloud data frame is sent to the main control computer (4).

3. The offshore transfer trestle wave compensation control system of claim 1, wherein: and laser beams of the laser sensors are always kept to be vertically and horizontally downward to shoot to the deck of the target ship.

4. The offshore transfer trestle wave compensation control system of claim 1, wherein: the filter (28) is a low-pass filter and is used for filtering high-frequency signals contained in the measurement signals of the attitude sensor (22) and the inclination angle sensor (21), which are caused by deck high-frequency vibration caused by the operation of equipment such as a ship main engine.

5. The offshore transfer trestle wave compensation control system of claim 1, wherein: the very short term forecast is a forecast of time within a control period.

6. The offshore transfer trestle wave compensation control system of claim 1, wherein: the working method of the relative movement measuring unit (23) comprises the following steps:

s1, preprocessing the point cloud data frame obtained by the 2D laser radar (2)

Firstly, intercepting each frame of point cloud data from within a scanning angle psi of a 2D laser radar (2) to obtain a point cloud data frame consisting of N distance data, wherein N is less than N; then, calculating an absolute value | Data [ m ] -Data [ m-1] | of the difference between the mth distance Data and the mth-1 distance Data in each frame of point cloud Data, and calculating a change rate ξ ═ Data [ m ] -Data [ m-1] |/Δ t, m ═ 2,3, …, n of the absolute value relative to a Data acquisition time interval Δ t; and then carry on the detection of the outlier according to this, if the board surface of the ship board top strake of the target ship and deck is smooth, have xi ≦ epsilon, epsilon is a certain appropriate threshold, when xi > epsilon, the data point is judged as the outlier, namely the unusual data point, is abandoned;

Firstly, in order to match a point cloud preprocessing data frame with a target ship reference data frame in still water, the point cloud preprocessing data frame needs to rotate by taking a characteristic point M as a center and translate along an X axis and a Z axis, and the rotation angle is recorded as theta and the translation amount along the X axis is recorded as D_xAnd a translation amount along the Z axis of D_zThe maximum angle of the rotation of the point cloud preprocessing data frame is theta in practice_m，θ∈[-θ_m,θ_m]If the step size is b, go through the whole [ -theta ]_m,θ_m]The number of steps required for the interval is U to int (θ)_mB), when the rotation angle theta (i) is b X (i-U), the point cloud preprocessing data frame obtained by the histogram translation method needs to be respectively translated along the X axis and the Z axis by D_x(i) And D_z(i) Calculating a matching error (i) between the point cloud preprocessing data frame and a target ship reference data frame in still water, wherein i is 0,1,2,3, … and 2U;

then, searching the minimum value of the matching error between frames in error (i), and when i is equal to i_eminWhen the error is minimum, the matching error between frames is recorded as error_min(i_emin) When theta is equal to theta (i)_emin) Matching the point cloud preprocessing data frame with a target ship reference data frame in still water, and outputting X-axis translation displacement D_x＝D_x(i_emin) And Z-axis translational displacement D_z＝D_z(i_emin)；

The distances from both sides of the front end of the transfer trestle bridge body to the deck of the target ship are respectively q according to the distances measured by the first laser sensor (37) and the second laser sensor (38)₁And q is₂And calculating the relative displacement D of the transfer trestle bridge front end and the transfer point on the target ship along the surging direction according to the sizes of the target ship and the boarding trestle bridge_Ty(ii) a According to the heave displacement, the sway displacement and the roll angle of the transfer trestle base (5) along with the host ship, which are measured by a position of the 2D laser radar (2) arranged on the host ship and an attitude sensor (22), the displacement D of the 2D laser radar (2) along with the host along the sway direction is calculated through wave disturbance_HxDisplacement in the heave direction D_Hz(ii) a Then the relative displacement S of the transfer trestle bridge body front end and the transfer point on the target ship along the swaying direction is obtained_x＝D_x-D_HxRelative displacement S along the surge direction_y＝D_TyRelative displacement S in the heave direction_z＝D_z-D_Hz。

7. A working method of a sea transfer trestle wave compensation control system is characterized in that: the method comprises the following steps:

A. after the target ship and the host ship are leaned against the upper, an operator controls each hydraulic motor to drive the rotating mechanism (9), the pitching mechanism (12) and the bridge body telescopic mechanism (14) according to information provided by the transfer point monitoring device (15), so that the front end of the bridge body of the transfer trestle moves to a position right above the transfer point of the target ship and suitable for safe lap joint of the bridge body of the transfer trestle;

B. an operator starts an active compensation mode of a transfer trestle wave compensation control system, and a first kinematics inverse solution module (32) solves an expected rotation quantity of a first hydraulic motor (8), an expected rotation quantity of a second hydraulic motor (11) and an expected rotation quantity of a third hydraulic motor (13) according to relative displacement of the front end of a current transfer trestle body and a transfer point on a target ship along a swaying direction, a surging direction and a heaving direction, which is obtained by a relative motion measurement unit (23), and heaving displacement, swaying displacement and swaying angle of a transfer trestle base (5) along with the ship, which are measured by an attitude sensor (22) in real time; the first encoder (16), the second encoder (17) and the third encoder (18) respectively feed back the actual rotation quantity of the first hydraulic motor (8), the actual rotation quantity of the second hydraulic motor (11) and the actual rotation quantity of the third hydraulic motor (13) in real time, the three-degree-of-freedom compensation controller (33) outputs control voltages of the first electro-hydraulic servo valve (24), the second electro-hydraulic servo valve (25) and the third electro-hydraulic servo valve (26) according to the expected rotation quantity and the actual rotation quantity, changes the valve opening, adjusts the flow of hydraulic oil of the three hydraulic motors, controls the cooperative motion of the slewing mechanism (9), the pitching mechanism (12) and the bridge body stretching mechanism (14), compensates disturbance of the swinging motion of two side boats on the sea transfer trestle in real time, realizes the follow-up of the front end of the bridge body of the transfer trestle and the transfer point on the target boat, and provides guarantee for the safe overlapping and fixing of the bridge body of the trestle at the transfer point;

C. after the transfer trestle bridge body is fixed at a transfer point on a target ship, an operator switches the transfer trestle wave compensation control system to a heave compensation mode, and according to the expansion amount of the expansion mechanism measured in real time by the third encoder (18), the included angle gamma between the transfer trestle bridge body and the horizontal plane measured in real time by the tilt angle sensor (21), the pitch angle of the pitching mechanism (12) measured in real time by the fourth encoder (20) and the expected safety angle gamma between the trestle bridge body and the horizontal plane_dThe second kinematics inverse solution module (35) calculates the expected telescopic amount of the hydraulic cylinder (6); according to the expected expansion amount and the actual expansion amount of the hydraulic cylinder (6) measured by the stay wire displacement sensor (19) in real time, the heave compensation controller (36) outputs the control voltage of the fourth electro-hydraulic servo valve (27), changes the opening of the valve, and adjusts the hydraulic oil flow of the hydraulic cylinder (6) to control the movement of the heave mechanism (7), thereby ensuring that the trestle bridge body and the horizontal plane always keep an expected safety angle unchanged.

8. The working method of the offshore transfer trestle wave compensation control system of claim 7, which is characterized in that: the method comprises the following steps: the relative displacement D of the transfer point on the front end of the bridge body of the transfer trestle and the target ship along the surging direction_TyThe calculation method of (2) is as follows:

let TV show the attitude of the target ship deck at the previous moment, T shows the position of the transfer point on the target ship deck at the previous moment, the front end P of the transfer trestle bridge body is aligned with the transfer point T on the target ship along the Z-axis direction at the previous moment, when the target ship generates pitching motion, the attitude of the target ship deck is changed into T ' V ', the transfer point on the attitude is changed into T ' position, the laser beam of the first laser sensor (37) is irradiated on the I point on the target ship deck, the laser beam of the second laser sensor (38) is irradiated on the J point on the target ship deck, the distances measured by the two sensors from the two sides of the front end of the transfer trestle bridge body to the target ship deck are q respectively₁、q₂；

In Δ IKJ, angle IKJ is 90 °, | KJ | ═ q₂-q₁And w is the distance between the first laser sensor (37) and the second laser sensor (38), and the calculation formula of the pitch angle of the target ship is as follows:

∠O′TV＝arctan(|O′V|/|TV|)＝arctan(D₄/D₃)

in Δ O ' TT ', | O ' T | ═ O ' T ' |, given in combination formula (1):

∠T′TR＝(180°-ρ)/2-arctan(D₄/D₃)

in Δ TT 'R, the angle T' RT becomes 90 °, then:

9. the working method of the offshore transfer trestle wave compensation control system of claim 7, which is characterized in that: the calculation method of the first inverse kinematics solution module (32) is as follows:

according to the kinematics principle, a homogeneous transformation matrix for transforming a coordinate system {0} of a trestle base (5) to a ground coordinate system { G } is as follows:

in the formula, S_heave、S_sway、δ_rRespectively measuring the heave displacement, the sway displacement and the roll angle of the transfer trestle base (5) along with the ship by the attitude sensor (22), S_surge、δ_p、δ_zThe transfer trestle base (5) is respectively the surging displacement, the surging angle and the bow angle along with the ship;

because the host ship is provided with the dynamic positioning system, the influence of the swaying, surging and yawing motions of the host ship on the transfer trestle is ignored; the transfer trestle is arranged near the center of the side board of the host ship deck close to the target ship, so that the influence of the pitching motion of the host ship on the transfer trestle is ignored; therefore, only the disturbance of the heave and roll motion of the host ship to the transfer trestle needs to be compensated, which only causes the heave displacement S of the transfer trestle base (5)_heaveA swaying displacement S_swayAnd roll angle delta_rAnd S is_surge＝0，δ_p＝0，δ_z0, so the matrix is transformed in a homogeneous way

The method is simplified as follows:

the rotation matrix of the coordinate system {0} of the transfer trestle base (5) relative to the geodetic coordinate system { G } is as follows:

the coordinate of the point A where the 2D laser radar (2) is located in the coordinate system {0} of the transfer trestle base (5) is (D)₁,D₂,h₁) And the homogeneous transformation matrix of the coordinate system {1} of the 2D laser radar (2) relative to the coordinate system {0} of the transfer trestle base (5) is as follows:

then the homogeneous transformation matrix of the coordinate system {1} of the 2D laser radar (2) relative to the coordinate system { G } of the earth is:

therefore, the coordinates of the point A where the 2D laser radar (2) is located in the geodetic coordinate system { G } are obtained as follows:

coordinates of a front end P point of the transfer trestle bridge body in a coordinate system {0} of the transfer trestle base (5) are (Lsin (alpha) cos (beta) + acos (beta), Lsin (alpha) sin (beta) + asin (beta), -Lcos (alpha) + h), and are recorded as:

the homogeneous transformation matrix of the coordinate system {2} at the front end of the transfer trestle bridge body relative to the coordinate system {0} of the transfer trestle base (5) is as follows:

in the formula (I), the compound is shown in the specification,

in order to transfer a rotation matrix of a coordinate system {2} at the front end of the trestle body relative to a coordinate system {0} of a trestle base (5), L is the current length of the trestle body, a is the radius of a trestle transfer platform (10), alpha is the current pitch angle of a pitching mechanism (12), beta is the current rotation angle of a slewing mechanism (9), and h is the current height of a heaving mechanism (7), the homogeneous transformation matrix of the coordinate system {2} at the front end of the trestle body relative to a ground coordinate system { G } is:

when the operator switches the transfer trestle to the active compensation working mode, the height h of the heave mechanism (7) of the transfer trestle₀A pitch angle alpha of the pitch mechanism (12)₀A rotation angle beta of the turning mechanism (9)₀And the transfer trestle base (5) heave displacement S_heave0A swaying displacement S_sway0Roll angle delta_r0All the coordinates are obtained by a measurement system, and then the coordinates of the point A at the position of the 2D laser radar (2) in the earth coordinate system { G } at the moment are known according to the formula (2)^GA₀＝[^GX_A0 ^GY_A0 ^GZ_A0]^TAccording to the formula (3), the coordinate of the front point P of the bridge body of the transfer trestle at the moment under the geodetic coordinate system { G }, is known^GP_tip0＝[^GX_tip0 ^GY_tip0 ^GZ_tip0]^TTo obtain a 2D laser radar (2) along the heave directionHas a displacement of D_Hz＝^GZ_A-^GZ_A0A displacement in the yaw direction is D_Hx＝^GX_A-^GX_A0；

When the target ship and the host ship are leaned against the side, the two ships are connected together through the cable and the fender, the target ship is restrained by the cable and the fender, the swaying, surging and yawing motions are ignored, the heaving, swaying and pitching motions cause the transfer point on the deck of the target ship to follow up, and the relative displacement S of the front end of the bridge body of the transfer trestle and the transfer point on the target ship along the swaying direction_xRelative displacement S along the surge direction_yRelative displacement S in the heave direction_zRemember S_m＝[S_x S_y S_z]^T；^GP_{tip_d}＝[^GX_{tip_d} ^GY_{tip_} _d ^GZ_{tip_d}]^TRepresenting the expected position of the front end P point of the transfer trestle bridge body in a geodetic coordinate system { G }; considering that the control target is to make the P point at the front end of the bridge body of the transfer trestle follow up with the transfer point on the target ship, the following steps are provided:

^GP_{tip_d}＝^GP_tip0+S_m (4)

the coordinate formula (3) of the point P at the front end of the transfer trestle bridge body under the geodetic coordinate system { G } is equal to the coordinate formula (4) of the expected position of the point P under the geodetic coordinate system { G }, and the expected rotation angle beta of the transfer trestle rotation mechanism (9) is obtained by solving_d＝f₁(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) A desired pitch angle alpha of the pitch mechanism (12)_d＝f₂(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) Desired length L of the telescopic mechanism_d＝f₃(^GX_{tip_d},^GY_{tip_d},^GZ_{tip_d}) The rotation angle of the rotary mechanism (9) to be compensated is delta beta-beta_d-β₀The pitch angle of the pitch mechanism (12) to be compensated is delta alpha-alpha_d-α₀The expansion amount of the expansion mechanism needing to be compensated is delta L ═ L_d-L₀；

According to the specific structures of the slewing mechanism (9), the pitching mechanism (12) and the bridge body telescopic mechanism (14), the expected rotation quantity eta of the first hydraulic motor (8) is obtained₁K is the transmission ratio between the rotation angle of the slewing mechanism (9) and the rotation quantity of the first hydraulic motor (8); desired rotation amount eta of second hydraulic motor (11)₂＝f₄(Δα)，f₄The (-) shows the transmission relation between the pitch angle of the pitch mechanism (12) and the rotation quantity of the second hydraulic motor (11); desired rotation amount eta of the third hydraulic motor (13)₃＝f₅(ΔL)，f₅The transmission relationship between the expansion amount of the expansion mechanism and the rotation amount of the third hydraulic motor (13) is shown.

10. The working method of the offshore transfer trestle wave compensation control system of claim 7, which is characterized in that: the calculation method of the second inverse kinematics solution module (35) is as follows:

let DP denote the attitude of the transfer trestle at the previous moment, and the expected angle between the transfer trestle and the horizontal plane is gamma_dThe front end P of the transfer trestle bridge body is fixedly connected with a transfer point on a target ship, and when the host ship and the target ship generate disturbance to the transfer trestle due to swinging motion, the posture of the transfer trestle bridge body is changed into DP', so as to ensure that the transfer trestle bridge body keeps a desired angle gamma with the horizontal plane_dThe ascending and descending mechanism (7) is actively controlled to stretch without changing, so that the posture of the bridge body of the transfer trestle is changed into D 'P';

in Δ DD 'P', we derive from the sine theorem:

in the formula, | DP '| is L, L is the current length of the transfer trestle bridge body, | DD' | Δ h, Δ h is the telescopic displacement of the heave mechanism (7);

when gamma is less than or equal to gamma_dWhen the angle D 'P' D is equal to gamma_d- γ and ═ P' D ═ α - (γ)_d- γ), from equation (5), the telescopic displacement of the heave mechanism (7)

According to the specific structure of the heave mechanism (7), obtaining the expected expansion and contraction quantity delta X of the hydraulic cylinder (6) as delta h;

when gamma > gamma_dWhen the angle D 'P' D is equal to gamma-gamma_d，∠P′D′D＝180°-[α+(γ-γ_d)]According to the formula (5), the telescopic displacement of the heave mechanism (7)

According to the specific structure of the heave mechanism (7), the expected expansion and contraction quantity delta X of the hydraulic cylinder (6) is obtained as minus delta h.